The primary mission of the magnetic resonance imaging (MRI) Core is to provide a detailed view of in vivo anatomy that is essential for the fulfillment of the objectives of the three Subprojects of this Program Project. Each MRI time point has been carefully selected to obtain specific information that will help to a) determine the severity of spinal cord injury, b) guide the transplant or vehicle injections, and c) determine transplant viability at key points (e.g., immediately prior to Cyclosporine A withdrawal). In addition, we will investigate the potential of MR microscopy for providing detailed 3-dimensional images of the injury or transplant site in selected postmortem spinal cord specimens. Since these data can be acquired in a time-efficient and cost-effective manner, we will assess the accuracy and reliability of MR microscopy for measuring important morphological parameters (e.g., lesion volume). Accordingly, the specific aims of this core are: (i) to provide in vivo anatomical views of the spinal cord at key time points during the injury and transplantation protocols, and (ii) to determine the ability of MR microscopy to provide reliable measures of several gross morphological parameters relevant to spinal cord injury and fetal tissue grafting. The MR images in Aim 1 will (a) provide an early evaluation of lesion severity by demonstrating hemorrhage and edema, (b) show lesion volume when locomotor function has stabilized, (c) show the lesion location and volume 1 week prior to delayed transplantation, which will assist greatly in determining the volume of the injection material, and (d) determine whether a viable graft is present 1 week prior to withdrawal of Cyclosporine A. Aim 2 will determine how accurately MR microscopy can illustrate lesion volume, transplant volume, and host- graft apposition, as well as white matter sparing in the adjacent host spinal cord. In addition, the noninvasive nature of the in vivo MRI studies underscores the clinical relevance of this Program Project, and the data obtained herein will be invaluable to any future cellular grafting approaches aimed at repair of human spinal cord injury.